Status of TEPCO's Nuclear Power Stations after the Tohoku-Chihou-Taiheiyou-Oki Earthquake (Daily Report as of 3:00 PM on August 11)

Due to the Tohoku-Chihou-Taiheiyou-Oki Earthquake which occurred on March 11, 2011, TEPCO's facilities including our nuclear power stations have been severely damaged. We deeply apologize for the anxiety and inconvenience caused.
With regard to the accident at Fukushima Daiichi Nuclear Power Station, on April 17, 2011, we have compiled the roadmap towards restoration from the accident and on July 19 we accomplished the Step1 target "Radiation dose is in steady decline". Then on December 16 we confirmed the accomplishment of the Step 2 target "Release of radioactive materials is under control and radiation doses are being significantly held down".
In addition, on December 21, 2011, we have compiled the "Mid-to-long-Term Roadmap toward the Decommissioning of Fukushima Daiichi Nuclear Power Units 1-4, TEPCO".
In addition to the maintenance of the plant's stable condition, we will implement Mid-to-Long Term countermeasures towards the decommissioning of Fukushima Daiichi Nuclear Power Units 1-4 to enable evacuees to return to their homes as soon as possible and reduce the anxiety of the people in Fukushima and the whole nation as soon as possible.

Below is the status of TEPCO's Fukushima Daiichi Nuclear Power Station.

* The updates are underlined.

[Fukushima Daiichi Nuclear Power Station]
･ Unit 1 to 4: Abolishment (April 19, 2012)
･ Unit 5 to 6: Outage due to regular inspections before the earthquake

- Contaminated water transfer from the underground reservoirs was all completed as of July 1. However, we are continuing to take measures to prevent the expansion of contaminated water, and to conduct sampling activities.

<Measures to prevent the expansion of contaminated water>
･ Since the decreases of all-β radioactivity densities in the leakage detection holes (at the northeast side of the underground reservoir No.1, the northeast side of the underground reservoir No.2, and the southwest side of the underground reservoir No.3) have been slow, operations to dilute the underground reservoirs No.1-No.3 by transferring filtered water or desalination-system (RO) treated water (the all-β radioactivity density: approx. 1×10¹Bq/cm³) into these reservoirs have been conducted as appropriate.
[Recent dilution operations]
Underground reservoir No.1 (since June 19): On August 3, approx. 60m³ of filtered water was injected.
Underground reservoir No.2 (since June 27): On August 1, approx. 60m³ of filtered water was injected.
Underground reservoir No.3 (since July 24): On August 5, approx. 60m³ of filtered water was injected.

･ On August 10, leaked water in the leakage detection holes at the underground reservoirs No.1-No.3 was transferred to the temporary aboveground tank, and leaked water in the drain holes at the underground reservoirs No.1 and No.2 was transferred into these underground reservoirs.

<Sampling>
On August 10, sampling was performed in the drain holes of the underground reservoirs No.1-No.7 (14 locations), the leakage detection holes of the underground reservoirs No.1-No.4 and No.6 (sample could not be collected at 2 out of 10 locations), and the observation holes of the underground reservoirs (22 locations). The analysis results showed no significant change compared to the results from the previous sampling (on August 9).

- We installed observation holes east of the Unit 1-4 Turbine Buildings, and have been conducting sampling and analysis of groundwater from the observation holes. On June 19, we announced that tritium and strontium were detected at high densities in the observation hole located between Units 1 and 2. Therefore, we have been conducting intensified monitoring.

･ At 2:10 PM on August 9, we started pumping up groundwater from the water collection pit (south) installed east of Units 1 and 2 Turbine Buildings and transferring the pumped-up groundwater to the Unit 2 vertical shaft C.

･ On August 10, we measured the groundwater level in the newly dug-up groundwater observation hole No.1-8 (located approx. 18m east of the groundwater observation hole No.1, approx. 2m west of the ground improvement area, and approx. 7m from the bank protection).
<Groundwater observation hole No.1-8>
･ O.P. +2,800mm (This is a provisional value because verification of the reference altitude is underway.)

･ The tritium density in water sampled on August 8 from the newly installed groundwater observation hole No.0-1 (east of Unit 1 Turbine Building) was measured again, and the γ nuclide, all-β and tritium densities in water sampled again from the same location on August 10 were measured.
<Groundwater observation hole No.0-1>
･ Sampling on August 8 (the second measurement):
Tritium  23,000Bq/L
･ Sampling on August 10:
Cesium-134 0.66Bq/L
Cesium-137 1.2Bq/L
All-β  290Bq/L
Tritium  34,000Bq/L
[Reference (previously announced on August 8 and 9)]
･ Sampling on August 8 (the first measurement):
Cesium-134 0.61Bq/L
Cesium-137 1.6Bq/L
All-β  210Bq/L
Tritium  23,000Bq/L

- At around 2:22 PM on August 10, an alarm went off indicating the suspension of a booster pump and the detection of leakage, when the second cesium adsorption apparatus (SARRY) was in operation. The booster pump has been continuously in operation. The site conditions were checked later, and a puddle was found around a leakage detector at the adsorption tower area although no abnormality was found in the operation status of the booster pump. Dew condensation was found on the adsorption tower and the piping equipment, and dew condensation water was found to have reached the leakage detector. Since the radiation dose rate of water in the puddle was at the same level as the ambient (background) radiation dose rate, we determined that dew condensation water formed the puddle. The water in the puddle was wiped out. No abnormality (with the flow rate, the pressure, etc.) has been found in the operation status of SARRY.

 

* Revised past progress

The aforementioned attachments are only available in Japanese.
We apologize for any inconvenience this may cause.